Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0567—Liquid materials characterised by the additives
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0568—Liquid materials characterised by the solutes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0569—Liquid materials characterised by the solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
  • H01M2300/0037—Mixture of solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
  • H01M2300/0028—Organic electrolyte characterised by the solvent
  • H01M2300/0037—Mixture of solvents
  • H01M2300/004—Three solvents
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the application belongs to the technical field of secondary batteries, and particularly relates to an electrolyte and a lithium ion battery.
• Lithium ion batteries are warmly favored by consumers because of their remarkable advantages such as high specific energy, high specific power, long cycle life and low self-discharge. They are widely used in portable electronic products such as mobile phones, digital cameras, personal computers and so on. At the same time, they have become an important choice in the field of power and energy storage, which is of great significance to the development of “low-carbon economy”.
• Lithium ion battery electrolyte is mainly composed of lithium salt and organic carbonate, and is the bridge between the positive and negative electrodes, and plays a role in transferring ions and conducting current in the battery.
• the lithium salt, solvent and additive would undergo irreversible reduction reaction on the surface of carbon negative electrode to form a passivation film.
• 1,3-propane sultone (PS) as a film-forming additive with high cost performance, has been widely used in lithium ion electrolyte.
• 1,3-propane sultone has certain limitations as a film-forming additive.
• the present application provides an electrolyte and a lithium ion battery.
• the application provides an electrolyte, including a solvent, a lithium salt and an additive
• the additive includes vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate, and a weight ratio of vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate is 1: 0.2-6: 0.01-5.
• the electrolyte does not include 1,3-propane sultone.
• a percentage mass content of vinylene carbonate is 0.01%-10% based on a total mass of the electrolyte being 100%.
• the weight ratio of vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate is 1: 0.5-4: 0.02-3.
• the weight ratio of vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate is 1: 1-3: 0.05-2.
• the lithium salt is selected from one or more of organic lithium salt and inorganic lithium salt.
• the lithium salt includes one or more of hexafluorophosphate, hexafluoroarsenate, perchlorate, lithium trifluorosulfonyl, lithium difluoro (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide and lithium tris (trifluoromethylsulfonyl) methyl.
• a concentration of the lithium salt in the electrolyte is 0.5%-2 M.
• the solvent includes at least two of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl formate, ethyl formate, ethyl propionate, propyl propionate, methyl butyrate and tetrahydrofuran.
• the application provides a lithium ion battery, including a positive electrode, a negative electrode and the above-described electrolyte.
• vinylene carbonate, 3,3′-[1,2-ethylene bis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate are added into the electrolyte in a specific proportion.
• These three substances have a synergistic effect on the electrolyte, which can decompose on the surfaces of the positive and negative electrodes to form a highly stable passivation film, effectively protect the positive and negative electrodes in the charging and discharging process of the battery, and can complex transition metal ions to avoid the formation of lithium dendrites and the separation of negative electrode material, thus effectively improving the high-temperature storage performance and cycle performance of the battery.
• it is especially suitable for the use of high-voltage lithium ion batteries.
• the application provides an electrolyte, including a solvent, a lithium salt and an additive
• the additive includes vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate, and a weight ratio of vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate is 1: 0.2-6: 0.01-5.
• the electrolyte is added with vinylene carbonate, 3,3′-[1,2-ethylene bis (oxy)] dipropionitrile and lithium difluoro (oxalate) borateare added in a specific proportion.
• These three substances have a synergistic effect on the electrolyte, which can decompose on the surfaces of the positive and negative electrodes to form a highly stable passivation film, effectively protect the positive and negative electrodes in the charging and discharging process of the battery, and can complex transition metal ions to avoid the formation of lithium dendrites and the separation of negative electrode material, thus effectively improving the high-temperature storage performance and cycle performance of the battery. And it is especially suitable for the use of high-voltage lithium ion batteries.
• the electrolyte does not include 1,3-propane sultone.
• the present application solves the problems caused by 1,3-propane sultone by removing 1,3-propane sultone from the electrolyte. Meanwhile, by adopting the combination of vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate (in a specific proportion), the performance defects caused by the removal of 1,3-propane sultone can be effectively remedied, and the storage performance and cycle performance of lithium-ion battery would be able to reach a better level.
• the additive only includes vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate.
• a percentage mass content of vinylene carbonate is 0.01%-10% based on a total mass of the electrolyte being 100%.
• the percentage mass content of vinylene carbonate is 0.01%-4% based on the total mass of the electrolyte being 100%.
• the weight ratio of vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate is 1:0.5-4:0.02-3.
• the weight ratio of vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate is 1:1-3:0.05-2.
• the lithium salt is selected from one or more of organic lithium salt and inorganic lithium salt.
• the lithium salt includes one or more of hexafluorophosphate, hexafluoroarsenate, perchlorate, lithium trifluorosulfonyl, lithium difluoro (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide and lithium tris (trifluoromethylsulfonyl) methyl.
• lithium difluoro (oxalate) borate is used as an additive, not as a lithium salt.
• the lithium salt is selected from fluorine-containing lithium salts.
• the concentration of the lithium salt in the electrolyte is 0.5%-2 M.
• the concentration of the lithium salt in the electrolyte is 0.9%-1.3 M.
• the concentration of the lithium salt is too low, the conductivity of electrolyte would be low, which would affect the rate and cycle performance of the whole battery system. If the concentration of the lithium salt is too high, the viscosity of the electrolyte would be too high, which is also not conducive to the improvement of the rate of the whole battery system.
• the solvent includes at least two of vinyl carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl formate, ethyl formate, ethyl propionate, propyl propionate, methyl butyrate and tetrahydrofuran.
• Another embodiment of the present application provides a lithium ion battery, including a positive electrode, a negative electrode and the electrolyte as described above.
• he positive electrode includes a positive electrode current collector and a positive electrode material, and the positive electrode material covers the positive electrode current collector to form a positive electrode material layer.
• the positive electrode material includes a positive electrode active material, a positive electrode binder and a positive electrode conductive agent.
• the positive electrode active material includes one or more of lithium cobalt oxide, nickel-cobalt-lithium-manganese ternary material, lithium iron phosphate and lithium manganate.
• the positive electrode active material is selected from lithium cobalt oxide and nickel-cobalt-lithium-manganese ternary materia.
• the charge upper limit voltage of the lithium ion battery is 4.5 V.
• the positive electrode conductive agent includes one or more of carbon black, acetylene black, conductive graphite, carbon nano tube and graphene.
• the positive electrode binder includes one or more of styrene-butadiene rubber, polyacrylic acid, polyvinyl pyrrolidone, polyvinylidene fluoride and polytetrafluoroethylene.
• the negative electrode includes a negative electrode current collector and a negative electrode material provided on the negative electrode current collector.
• the compacted density of the negative electrode material is 1.6-1.85.
• the compacted density of the negative electrode material is 1.75-1.85.
• the negative electrode material includes a negative electrode active material, a negative electrode conductive agent and a negative electrode binder.
• the negative active material includes one or more of carbon material, metal alloy, lithium-containing oxide and silicon-containing material.
• the negative active material is selected from graphite.
• the negative conductive agent includes one or more of carbon black, acetylene black, conductive graphite, carbon nano tube and graphene.
• the negative electrode binder includes one or more of styrene-butadiene rubber, polyacrylic acid, polyvinyl pyrrolidone, polyvinylidene fluoride and polytetrafluoroethylene.
• the lithium ion battery further includes a separator disposed between the positive electrode and the negative electrode.
• the lithium ion battery provided by the embodiments of the application can effectively work with improved storage performance and cycle performance .
• the embodiment is used to illustrate the electrolyte, lithium ion battery and its preparation method disclosed in this application, including the following steps.
• Ethylene carbonate (EC), diethyl carbonate (DEC) and propylene carbonate (PC) were mixed in a mass ratio of 1: 1: 1 as an organic solvent.
• Additives of Embodiment 1 shown in Table 1 were added to the organic solvent and mixed evenly, then LiPF 6 was added, and an electrolyte with LiPF 6 concentration of 1.1 mol/L was obtained.
• the positive electrode active material lithium cobalt oxide (LiCoO 2 ), conductive agent carbon nano tube (CNT) and binder polyvinylidene fluoride were fully stirred and mixed in the solvent N-methyl pyrrolidone according to the mass ratio of 97:1.5:1.5 to form an uniform positive electrode slurry.
• the positive electrode slurry was uniformly coated on the positive electrode current collector Al foil, and then dried and cold pressed to obtain a positive electrode plate.
• the negative electrode active material graphite, conductive agent acetylene black, binder styrene-butadiene rubber and thickener sodium carboxymethyl cellulose were fully stirred and mixed in deionized water solvent according to the mass ratio of 95:2:2:1 to form an uniform negative electrode slurry.
• the slurry was coated on the negative electrode current collector Cu foil, then dried and cold pressed until the compacted density was 1.75, and a negative electrode plate was obtained.
• the positive electrode plate, separator film and negative electrode plate were stacked in sequence, so that the separator film was in the middle of the positive electrode plate and negative electrode plate, playing a separation role, and then a bare battery cell was obtained by winding.
• the bare battery cell was put into an outer packaging bag, then the electrolyte was injected into the dried cell, and after the processes of vacuum packaging, standing, formation, shape-making and the like, the preparation of lithium ion battery was completed.
• Embodiments 2-8 are used to illustrate the electrolyte, lithium ion battery and the preparation method disclosed in this application, including the steps of Embodiment 1, with the differences that:
• Comparative examples 1-6 are used to illustrate the electrolyte, lithium ion battery and the preparation method disclosed in this application, including the steps of Embodiment 1, with the differences that:
• the batteries were full charged at room temperature, and the original thicknesses were recorded. Then the batteries were put in an oven at 60° C. for 21 days for the thickness test of battery at hot status.
• Battery expansion rate (%) (thickness of hot battery after 21 days - initial battery thickness) / initial battery thickness *100%
• the batteries were put in an oven with a constant temperature of 25° C., and charged to 4.5 V at 1C constant current and constant voltage, then discharged at 1C. The above was repeated for 300 cycles.
• Capacity retention rate (%) discharge capacity (mAh) of different cycles / discharge capacity (mAh) of the 300th cycle * 100%
• the electrolyte provided by the present application can significantly improve the high-temperature storage performance and cycle.
• Embodiments 6 Compared with the test results of Embodiments 1-7, the performance of battery provided by Embodiments 6 is the best. And the weight ratio of vinylene carbonate, 3,3′-[1,2-ethylenebis (oxy)] dipropionitrile and lithium difluoro (oxalate) borate is 1: 2: 0.1, indicating the combination of this three additives in this ratio is the best.
• Embodiment 8 PS is added on the basis of Embodiment 6 to obtain Embodiment 8.
• Embodiment 8 which is completely free of PS, the differences between the storage performance and cycle capacity of Embodiment 8 are small, which indicates that PS can be removed from preparation of the technical solutions provided by the application, and the lithium ion batteries prepared after the removal of PS also meet the requirements on high-temperature storage performance and cycle performance.

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• 2020
  • 2020-06-17 CN CN202010554801.8A patent/CN113809396B/zh active Active
• 2021
  • 2021-06-17 WO PCT/CN2021/100682 patent/WO2021254451A1/fr unknown
  • 2021-06-17 EP EP21826481.0A patent/EP4170770A4/fr active Pending
• 2023
  • 2023-04-06 US US18/131,506 patent/US20230246235A1/en active Pending

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